1. Field of the Invention
The present invention relates to a process for preparing a ginkgo leaf tea and, more specifically, relates to a process for preparing a ginkgo leaf powder tea from which 2-hexenal has been eliminated and whose palate has been improved.
2. Description of Related Art
It is well known that a ginkgo tree contains many physiologically active components. For example, a ginkgo nut contains phenolic compounds, ginkgo, ginkgolic acid, etc., while a ginkgo leaf contains various aromatic compounds including phenolic compounds, flavonoid glycosides, simple flavonoids such as kaempferol, quercetin, isoramnetin and luotelin, and terpenoid compounds such as ginkolides.
Since the discovery that ginkgo leaf extract facilitates blood circulation in guinea pigs (see: Arzneimittel Forschung, 16:719(1966)), studies on ginkgo leaves have been extensively carried out in the art. In addition, ginkgo leaf extract is commercially available as a medicament in many countries. Ginkgo leaf extract has been reported to be highly effective for treating Burger's disease, diseases caused by disorders in peripheral blood circulation, astigmatism, bradyacusia, disorders in physical coordination, and coldness of limbs in aged people, cerebral infarction caused by disorders of blood circulation in brain, dementia, limb paralysis, etc.
As illustrated above, ginkgo leaves, which have many beneficial components for the human body, are being actively studied as possible active ingredients in medicine. However, heretofore, ginkgo leaves have not been manufactured as foodstuff additives from which the above-described beneficial components can be utilized. In particular, the use of ginkgo leaves as foodstuff additives has been proven to be less than satisfactory because, inter alia, ginkgo leaves have a bitter taste and a flavor that many people find objectionable. In addition, ginkgo leaves include a toxic 2-hexenal component which, however, is also known to be an anti-bacterial and anti-viral material. Thus, for at least these reasons, there have been obstacles in utilizing ginkgo leaves as raw materials for foodstuffs (see: T. Kosuge and N. Yokota, Yakuyaku Zasshi, 83:422(1963)). Accordingly, there exists a need for exploring and developing a novel process for the preparation of ginkgo leaves with an improved palate and safety, to solve the problems existing in the art.